Constitutional challenges to new state energy policies have been mounting in state and federal courts. This Article surveys the state of the relevant law, focusing on the dormant Commerce Clause and the Supremacy Clause, and draws five conclusions to guide states in achieving their energy policy goals: (1) locational requirements may be valid if based on reasons other than economic protectionism; (2) locational requirements may be valid if they do not impede interstate commerce or if the benefiting in-state economic interests do not compete with out-of-state businesses; (3) policies should place legal obligations only on instate entities and may also set standards for entities that voluntarily do business with in-state entities; (4) because wholesale power prices are regulated by FERC, state policies that set a wholesale price may be preempted; and (5) limited incentives for fuel-efficient commercial vehicle fleets are permissible.